Catalyst for preparation of unsaturated aldehydes and acids

ABSTRACT

Unsaturated acids and aldehydes, as acrylic acid and acrolein, are prepared together in excellent yields by the oxidation of an olefin as propylene in the presence of a catalyst containing a IIA metal molybdate, as strontium molybdate, tellurium oxide and phosphorus pentoxide.

United States Patent Eden *June 13, 1972 [54] CATALYST FOR PREPARATIONOF 51 Int. Cl. ..B0lj 11/82 UNSATURATED ALDEHYDES AND [58] lield ofSearch ..260/533 N, 604; 252/435, 437 ACIDS [56] References Cited [72]inventor: Jamal S. Eden, Akron, Ohio UNITED STATES PATENTS [73]Assignee: The B. F. Goodrich Company, New York,

NY, 3,387,038 6/1968 Koch ..252 437 x 3,451,945 6/1969 Eden ..252/437 1Notice: The Portion of the term of this Patent 3,417,125 12/1968 Eden..252 437 x sequent to June 24, 1986, has been disclaimed' PrimaryExaminer-Patrick P. Garvin [22] Filed: Feb 27, 1970 Altorney--J. HughesPowell, Jr. and Ernest K. Bean 21 App1.No.: 18,397 57 ABSTRACT Relaed sApplication D Unsaturated acids and aldehydes, as acrylic acid andacrolein, are prepared together in excellent yields by the oxidation ofan Dlvlslof of 663,557, 1967 which olefin as propylene in the presenceof a catalyst containing a commuanon-m'pan of 483,862, 30, "A metalmolybdate, as strontium molybdate, tellurium oxide 1965, Pat. No.3,401,198. and phosphorus pentoxide.

[52] U.S. Cl ..252/435, 25 2/437 1 Claim, N0 Drawings CATALYST FORPREPARATION OF UNSATURATED ALDEHYDES AND ACIDS CROSS REFERENCE TORELATED APPLICATION This is a division of application Ser. No. 663,557,filed Aug. 28, 1967, which in turn is a continuation-in-part ofapplication Ser. No. 483,862, filed Aug. 30, 1965, now US. Pat. No.3,401,198.

BACKGROUND OF THE INVENTION In my US Pat. No. 3,401,198, there isdisclosed a method for preparing unsaturated aldehydes and unsaturatedcarboxylic acids by oxidation of unsaturated hydrocarbons at an elevatedtemperature in the presence of a catalyst containing molybdenum oxide,tellurium oxide and an alkaline earth Group llA metal phosphate.

SUMMARY OF THE INVENTION I have now found that when olefins such aspropylene are reacted with oxygen at an elevated temperature in thepresence of a catalyst containing a Group IIA metal molybdate, such asstrontium molybdate, tellurium oxide and phosphorus pentoxide, thatexcellent conversion and yield of propylene to both acrylic acid andacrolein are obtained. While strontium molybdate is a preferredmaterial, barium and calcium molybdate are also useful. Control of theratio of aldehyde/acid by varying reaction conditions with the strontiumand barium catalysts provides a useful and economical system.

DETAILED DESCRIPTION The reactants for providing aldehydes are propyleneor isobutylene, a molecular oxygen-containing gas which can be pureoxygen, oxygen diluted with an inert gas, oxygen enriched air or air,per se.

Stoichiometric ratios of oxygen to olefin for the purposes of thisinvention are 1:1. While lower ratios of oxygen can be used at asacrifice of yield it is preferred to use about one-third to two-thirdsexcess oxygen. Large excesses of oxygen, while not undesirable,introduce process problems and require larger equipment. An amount ofoxygen from about 1 to about 4 mols ofoxygen per mol ofolefin is anadequate range.

The use of steam in the reaction while desirable is not absolutelyessential. The amount of steam used may be varied from about to or moremols per mol of olefin. Other diluent gases such as nitrogen, saturatedhydrocarbons such as propane or butane may be used if desired.

The reaction may be carried out in either fixed or fluidized catalystbed.

The reaction temperature can range from about 300 C. to about 500 C. Apreferred range is from about 350 C. to about 450 C.

The contact time may vary considerably in the range of about 2 to 70seconds. Good results have been obtained within the range of about 10 toabout 50 seconds.

The reaction may be conducted at atmospheric pressure, in a partialvacuum, or under induced pressures up to 100 psi or higher. Atmosphericpressure is preferred for fixed bed systems and higher pressures forfluid bed reactions.

The particle size of the catalyst for fixed bed operations may be fromabout 10 to 18 mesh. Larger and smaller size particles may be used infixed beds if desired. For fluid bed operations, the catalyst sizenormally will range from about 80 to 325 mesh (U.S. Sieve).

The catalyst containing, strontium molybdate for example, telluriumoxide and phosphorus pentoxide may be prepared by a number of methodsand may be supported or unsupported. The catalyst ingredients may bemixed in the form of solutions or slurries, or can be dry blended.

A general procedure for preparing the catalyst is to make a slurry ofthe HA metal molybdate, add a slurry of ammonium tellurate thereto, andthen add phosphoric acid. The resulting mixture is evaporated to drynesson a steam bath, calcined in a hot tube oven for 16 hours at 400 C. to425 C., cooled to room temperature and meshed to the desired size.

Supported catalysts may be prepared by adding a dry support or aqueousslurry thereof to the catalyst ingredients. Alternatively, powderedmolybdate and ammonium tellurate may be mixed with phosphoric acid, adry support added thereto and dried.

Among suitable supports are silica, silica-containing materials such asdiatomaceous earth, kieselguhr, silicon carbide, clay, aluminum oxidesand the like.

Specific catalyst compositions used in the Examples herein were preparedby mixing one mol of IIA metal molybdate in a water slurry with 89.2grams of ammonium tellurate in a water slurry and then 1 15.3 grams of HPO The resulting mixtures were evaporated to dryness on a steam bath andcalcined in a hot tube oven overnight at 400 C. to 425 C. The catalystwas ground to a mesh size to 10 to 18 mesh (U.S. Sieve). This catalystcontained a molar ratio of IIA molybdate, 33 tellurium oxide and 50phosphorus pentoxide. Catalysts with molar ratios of 100 IIA metalmolybdate, 10100 tellurium oxide and 10-100 phosphorus pentoxide areuseful in oxidizing propylene or isobutylene to acrolein and acrylicacid or methacrolein and methacrylic acid in excellent yields. Betterresults have been obtained with SrMoO, and BaMoO As an Example ofdemonstrating preparation of a supported catalyst containing the IIAmetal molybdate the ammonium tellurate and phosphoric acid there isadded to the aqueous dispersions described above 315 grams of a 30-35percent colloidal dispersion of microspheroidal silica (Ludex H.S.) isadded slowly with stirring. After thorough mixing the catalyst is driedas described above. This provides, on a molar basis, in these catalysts180 SiO Another procedure is to add the mixture of ingredients to theLudox or the ingredients may be added to the Ludox individually.

EXAMPLE I A series of runs was made in a fixed bed reactor of a highsilica (Vycor) glass tube 12 inches long and 30 mm. outer diameter. Thereactor had inlets for air, steam and propylene. External electricallyoperated heating coils were wound on the reactor. Outlet vapors werepassed through a water cooled condenser and the uncondensed gases werepassed through a gas chromatograph and analyzed continuously. The liquidcondensate was weighed and analyzed for unsaturated acid and aldehyde inthe gas chromatograph. Ml. of catalyst prepared as described above andcontaining 100 SrMoO,, 33 TaO and 50 P 0 was placed in the reactor.Steam at a temperature of 200 C. to 250 C. was first fed into thereactor, and thereafter propylene and air were separately fed into thereactor from preheaters at a temperature of about 200 to 250 C. Beforethe propylene was added, the reactor was preheated to about 285 C. Themolar ratio of reactants used was one mol of propylene, 4.2 mols ofsteam and 3.04 mols of oxygen. The reaction temperature, contact time(calculated at room temperature and pressure), conversion and yieldobtained in the several runs are set forth in Table I.

When this Example is repeated with isobutylene instead of propylene,good yields of methacrolein and methacrylic acid are obtained at 450 C.

EXAMPLE II A series of runs was made in the fixed bed reactor of Examplel. 170 M1. of catalyst prepared as described above containing 100 BaMoO33 T and 50 P 0 was placed in the reactor. The molar ratio of reactantsused was one mol of propylene, 4.2 mols of steam and 3.04 mols ofoxygen. The reaction temperature, conversion, contact time (calculatedat room temperature and pressure) and yields in the several runs are setforth in Table II below.

The acrylic acid potential of Run 3 is about 77.5 percent by recycle ofthe reactor efiluent.

EXAMPLE III A series of runs was made in a fixed bed reactor asdescribed in Example I. 170 M]. of catalyst prepared as described abovecontaining CaMoO 33 TeO and 50 P 0 was placed in the reactor. The molarratio of reactants used was one mol of propylene, 4.2 mols of steam and3.04 mols of oxygen. The reaction temperatures, contact time (calculatedat room temperature and pressure), conversion and yield in the severalruns is set forth in Table II].

TABLE III Run Temp.

Contact Mol Mol Yield on C. Time Propylene Propylene Converted SecondsConverted Acrolein Acrylic Acid I claim:

1. A catalyst consisting essentially of, on a molar basis, 100 SrMoOBaMoO or CaMoO. with lO-lOO TeO and 10-100 P 0

